This disclosure relates generally to hoists. More particularly, this disclosure relates to translating body rescue hoists for aircraft.
Rescue hoists deploy and retrieve a cable from a cable drum to hoist persons or cargo, and the rescue hoist may be mounted to an aircraft, such as a helicopter. The rescue hoist includes a drum off of which the cable is deployed. The cable drum rotates to spool or unspool the cable from the cable drum, with one end of the cable attached to the cable drum and the other end, which can include a hook or other device, deployed during operation. The cable should be levelly wound onto the cable drum to prevent fouling of the cable and to prevent the cable from experiencing extra strain. To levelly wind the cable onto the cable drum, either the cable drum or a payout block translates during cable winding and unwinding to ensure that the cable is properly aligned on the cable drum. To ensure that the cable is levelly wound either the cable drum or the payout block is attached to and follows along a level wind mechanism, which is typically a dual-threaded screw such as a diamond screw, yankee screw, or reversing screw. Dual-threaded screws include inherently sharp features where the grooves intersect, which can fracture due to vibration leading to the follower prematurely reversing direction, causing a cable miswrap on the cable drum.